1. Field of the Invention
The field of the invention relates to the regulation of the growth of aquatic weeds in canals, rivers, ponds, lakes and impoundments.
2. Description of the Prior Art
The problems of controlling or regulating the growth of organisms in aqueous systems are serious and growing in severity. Submerged aquatic weeds, for example, cause major problems in water distribution and irrigation systems. The growth of such weeds in irrigation canals greatly reduces the conductivity and capacity of such systems with resulting substantial economic loss. Large sums are spent in the mechanical and other methods of removal of weed growths from irrigation canals, especially in the western parts of the United States. Because of the great difficulties involved in the mechanical removal of weeds and other undesired forms of aquatic life from irrigation canals, ponds, lakes, impoundments, etc., it has been proposed to utilize chemical control. Accordingly, various types of chemicals have been added to such bodies of water.
However, with the present emphasis on conservation, current efforts are directed toward regulating the growth, that is, limiting or inhibiting the amount of growth accomplished by the naturally occurring submerged or floating aquatic weeds without killing those weeds. This approach is being taken in order to continue to provide the natural environment for fish and other forms of marine life. A further reason is to avoid the masses of dead and rotting aquatic weeds which result when said weeds are killed by means of an aquatic herbicide, since the decomposition of the weeds decreases the amount of available oxygen present in the water. Such decaying matter, when it occurs in reservoirs and/or streams or lakes from which drinking water for cities is obtained, makes purification of the water much more difficult. Such decaying vegetation gives off an unpleasant odor when it collects in a body of water. Thus, a control of the amount of growth rather than a destruction of the submerged or floating aquatic weeds serves to overcome both pollution of the water and pollution of the air.
In the prior art, Krumkalns et al., U.S. Pat. No. 3,655,359 Apr. 11, 1972), teach the use of substituted 3-pyridylmethanes for the inhibition of the growth of the unwanted weed seeds and seedling weeds. There is no teaching in the reference that 2- and 4-substituted pyridinemethane or -methanol compounds would act to control the growth of submerged or floating aquatic weeds.
Also in the prior art, Krumkalns et al., U.S. Pat. No. 3,744,988 (July 10, 1973), teach the use of substituted 3-pyridylmethanes in a method for inhibiting sucker growth to tobacco plants. This patent is a division of U.S. Pat. No. 3,655,359, supra, and includes in its disclosure many of the same compounds disclosed in the immediately previously identified patent. There is no teaching in this reference that 2- and 4-substituted pyridinemethane or -methanol compounds would act to control the growth of submerged or floating aquatic weeds.
Van Heyningen, U.S. Pat. No. 3,396,224 (Aug. 6, 1968), teaches a method of controlling fungi pathogenic to plants by contacting the fungus-susceptible plant with a fungicidal amount of a 3-pyridylmethane derivative, mainly a 3-pyridinemethanol. I have found many of the compounds disclosed in this reference are active as aquatic growth regulators. However, there is no teaching in this reference that 2- and 4-substituted pyridinemethane or -methanol compounds would be active as aquatic growth regulators.
Van Heyningen et al., U.S. Pat. No. 3,397,273 (Aug. 13, 1968), teaches and claims a method for protecting plants from attack by phytopathogenic fungi by treating the plants with a fungicidally-effective amount of a 3-pyridylmethane. This reference makes no suggestion that 2- and 4-substituted pyridinemethane or -methanol compounds would be active as growth regulators of submerged or floating aquatic weeds.
Krumkalns, U.S. Pat. No. 3,335,148 (Aug. 8, 1967), discloses and claims the 9-(3-pyridyl) derivative of fluorene, 9-fluorneol, xanthene, 9-xanthenol, and the corresponding nonphytotoxic acid addition salts thereof alleged to be useful as antifungal and antibacterial agents. There is no teaching or suggestion in this reference that the 2- and 4-substituted pyridinemethane or -methanol compounds would be active as growth regulators of submerged or floating aquatic weeds.
Yet another reference, krumkalns, U.S. Pat. No. 3,361,753 (Jan. 2, 1968), is directed to 9-(3-pyridyl)-thioxanthene and thioxanthol derivtives, active as plant antifungal agents and as antibacterial agents. There is no teaching in this reference that the 2- and 4-substituted pyridinemtahene or -methanol compounds would be active as regulators of the growth of submerged or floating aquatic weeds.
A few 2-, 3-, and 4-substituted pyridinecarbinols are taught by Biel et al., U.S. Pat. No. 3,409,629 (Nov. 5, 1968), and are alleged to be active as hypocholesteremic agents. There is no teaching or suggestion that such compounds would be active to control the growth of submerged or floating aquatic weeds.
Another reference is German Pat. No. 1,935,292, also identified by Derwent No. 04548S, which patent teaches and claims a means for controlling plant growth, that is, restraining growth and influencing the habits of higher plants, influencing blossom and fruit formation, checking the growth of grass, and the like, using tri-arylmethylimidazoles, -pyrazoles, and -triazoles, or their salts. One of the aryl groups is taught as pyridyl. The reference does not appear to include use on aquatic weeds or plants.
Yet another reference is British Pat. No. 1,274,578, also identified by Derwent No. 23143S. This reference teaches plan growth regulators containing N-benzylimidazoles, wherein one of the substituents is a pyridyl group. These compounds are alleged to be plant growth regulators capable of inhibiting or accelerating growth, flowering and fruiting, according to the amount applied. Certain of the compounds are also alleged to be plant fungicides and bactericides.